Tim Mayza: Blue Jays’ lefty reliever of the future, today

It may surprise you to know just how good Tim Mayza has been for the Blue Jays

Blue Jays fans were first introduced to reliever Tim Mayza during the early days of Spring Training 2017, with his mid-90s fastball the main attraction. Through his first four games, Mayza struck out five of the 14 batters he faced, running an impressive 35% strikeout rate (though generally against other minor leaguers).

Those strong early performances led me (in my third post blogging about the Blue Jays) to examine the usefulness of lefty relievers with mid-90s fastballs. My main takeaway was that, at least from the left side, there’s a noticeable jump in fastball effectiveness around 94mph. In particular, strikeout rates increase and home run rates fall, resulting in much lower-than-average ERA and FIP. These findings bolstered my confidence in Mayza and the likelihood that he could develop into a solid MLB reliever.

What I did not expect was how quickly that initial development has happened—when I first wrote about him, he had all of 15.1 IP at Double-A. Obviously, it’s important to note that player development is non-linear. Early success can be followed by struggles, which themselves might be followed by more struggles or renewed successes. Nevertheless, it’s also obvious to state that early success is more predictive of future success than early failure—all else equal, you’d prefer to see your team’s youngsters performing well in their first taste of the bigs. Fortunately, based on pretty much all metrics, Tim Mayza has experienced early success as a big leaguer.

Let’s start with the fastball that piqued my interest a year and a half ago. Thus far into his major league career, Mayza’s four-seamer has averaged 93.9mph. That’s a good sign, considering the jump in performance I found among lefty relievers with a 94mph fastball.

Mayza’s quality performances shine most clearly through his strikeout rate. As a big leaguer, he’s struck out 29.5% of the batters he’s faced, putting him in the 84th percentile among left-handed relievers with 50+ IP over 2017-18. For perspective, the average lefty reliever over the last two seasons has produced a 22.9% K rate. When it comes to strikeouts, Mayza doesn’t really care whether he’s up against a lefty or a righty—he’s produced a 31.3% K rate vs. LHH and a 28.2% K rate vs. RHH, both well above-average marks.

While his walk rate isn’t quite so special, it doesn’t need to be—when a pitcher strikes out nearly a third of batters, an average walk rate is more than sufficient. Mayza actually sports a better-than-average walk rate for his career, a 7.9% mark that puts him in the 71st percentile (the average LHRP runs a 9.6% walk rate). In this case, the lefty-righty split is a bit greater—he’s only walked a stingy 4.2% of LHH, but has given a free pass to 10.7% of the righties he’s faced. While his walk rate against LHH is clearly strong, his walk rate against RHH actually isn’t all that bad—the average LHRP walks 10.2% of the RHH he faces.

One result of Mayza’s strong strikeout and walk rates is an excellent K-BB%. His 21.6% mark puts him in the 85th percentile among LHRP over the last two seasons. Mayza has faced plenty of righties, producing a better-than-average K-BB% against them (17.6% vs. a LHRP average of 11.6%). However, he stands out even more so against LHH—his 27.1% K-BB% against lefties is well above-average (16%), ranking in the 89th percentile. There is a short, star-studded list of LHRP who have produced a better K-BB% against LHH than Mayza has over the last two seasons (among those who have faced at least 75 lefty hitters): Felipe Vazquez, Sean Doolittle, Brad Hand, Josh Hader, Aroldis Chapman, Tony Cingrani, A.J. Minter and Mike Minor.

Clearly, when the ball is not put in play, Tim Mayza has produced excellent results. On batted balls, the picture is somehwat murkier, but increasingly positive. For example, over his career, Mayza has given up 1.05 HR/9, above the average for LHRP (0.98). However, that total was skewed by a rough debut season in 2017 (1.59 HR/9). This season, Mayza has actually given up dingers less often (0.78 HR/9) than the average LHRP (0.89 HR/9).

A big part of this improvement has been generating weaker batted balls by right-handed hitters. Last season, against the 42 righties he faced, Mayza gave up a total of three homers (3.11 HR/9). This season, he’s faced more than double the number of righties (89), but has given up only two homers (0.93 HR/9). Similarly, Mayza has been able to improve his ISO against this season (down to .129 from .200 in 2017), now boasting a better-than-average mark, thanks mainly to improvements against RHH (down to .160 from .351).

This improvement is also evident in Mayza’s Statcast numbers. Last season, he gave up a lot of high-quality contact. Lefties hit him reasonably well, producing a .367 xwOBA on batted balls against him (compared to the LHRP vs. LHH average of .333). On the other hand, righties absolutely clobbered him when they made contact, producing a .535 mark (against a LHRP vs. RHH average of .361). This season, hitters are struggling to generate good contact, allowing Mayza to produce better-than-average marks against both LHH (.318) and RHH (.348).

Examining his overall performance through two partial seasons in the bigs requires a look at a few statistics, as his ERA doesn’t tell the full story. According to that ERA (4.53), Mayza has had a rough start to his major league career, with that mark ranking in the 21st percentile among LHRP over the last two seasons (minimum of 50 IP). On the other hand, his FIP (3.23) is solid, ranking in the 75th percentile, driven by those strong strikeout and walk rates.

His inflated BABIP explains much of the discrepancy between his career ERA and FIP. His .373 BABIP puts him in the 2nd percentile among lefty relievers and is much, much higher than that of the average LHRP (.304). Fortunately, we can say with confidence that his BABIP was far higher than it “should” have been—his xBABIP was only .316. This suggests that, all in all, his FIP has been more reflective of his true performance thus far than his ERA.

His poor batted ball luck is also reflected in the wOBA and xwOBA he’s allowed overall. Like his ERA, Mayza’s wOBA (.324, 32nd percentile) suggests that he’s struggled to achieve good results thus far. Like his FIP, Mayza’s xwOBA (.287, 80th percentile) reveals that he’s actually been a very good lefty reliever in the early days of his major league career, conceding much weaker contact than his results would imply. His relatively high career wOBA is, in truth, skewed by his 2017 struggles—in 2018, Mayza has limited hitters to a .298 wOBA (56th percentile), supported by a strong .272 xwOBA (84th percentile).

Over his short career, he’s already begun to establish himself as a lefty who can take care of lefties as well as anyone. He’s produced an exceptional FIP (1.80, 93rd percentile), thanks to his strong strikeout (31.3%, 79th percentile), walk (4.2%, 91st percentile) and home run (0.38 HR/9, 77th percentile) rates against left-handed hitters. His strong strikeout and walk rates, combined with an above-average ability to prevent lefties from getting any type of base hit (.325 wOBA on batted balls, 59th percentile) has helped him produce a strong overall wOBA against them (.243 wOBA, 87th percentile). Moreover, the underlying contact he’s conceded has been relatively weak (.335 xwOBA on batted balls, 57th percentile), driving his very strong .249 xwOBA overall against LHH (85th percentile).

For illustrative purposes, let’s look at the recent success that lefty reliever Aroldis Chapman has had against left-handed batters. Over the last two seasons, he’s faced 115 left-handed batters for the Yankees. He’s produced a 2.58 FIP, limiting left-handers to a .261 wOBA and a .279 xwOBA. If you take a peek up at the last paragraph, you’ll notice that Mayza bests him in all three metrics. While Chapman has been more effective at striking lefties out (41.7% K rate), he has been less effective at limiting walks (9.6% walk rate). He’s also given up homers more often (0.64 HR/9), allowed poorer results on batted balls (.354 wOBA on batted balls) and conceded higher-quality contact (.397 xwOBA on batted balls) than Mayza has against lefties.

I am not saying that Tim Mayza is a better pitcher than Aroldis Chapman. What I am saying is that Tim Mayza has been better against lefties than Aroldis Chapman over the last two seasons, in spite of the fact that 1) he was facing the first 96 big league LHH of his career and 2) since his first pitch in the majors, he’s been demoted and recalled seven times.

In his second season, both his walk (9.5%, 49th percentile) and strikeout rates (27%, 73rd percentile) diminished some, but the quality of contact that he surrendered weakened significantly (.335 xwOBA on batted balls, 76th percentile), resulting in much fewer base hits (.376 wOBA on batted balls, 36th percentile). As a result, Mayza improved upon his ERA (3.38, 27th percentile) and posted better-than-average wOBA (.298, 58th percentile) and xwOBA (.272, 85th percentile). His FIP rose a little (3.35, 59th percentile), but remained solid.

As a big leaguer, Tim Mayza has been an above-average lefty reliever, in terms of xwOBA and FIP, when he’s been in the lineup. In lefty-on-lefty matchups, Mayza’s quality has been even more evident, with his FIP, wOBA and xwOBA each ranking among the league leaders. If this is who Mayza is, fantastic. On the other hand, if there is some development left in him, particularly in matchups against right-handed batters, it’s not hyperbole to say that he has the potential to develop into one of the best left-handed relievers in baseball.